Heat-sensitive adhesive material

Abstract

The present invention is to provide a heat-sensitive adhesive material containing a support;,and an adhesive under layer, an intermediate layer and a heat-sensitive adhesive layer formed over one surface of the support in this order, wherein the intermediate layer contains at least a thermoplastic resin and hollow particles, the heat-sensitive adhesive layer contains at least a thermoplastic resin, an adhesion imparting agent and a thermofusible material, and the adhesive under layer contains at least a thermoplastic resin, the thermoplastic resin has a glass transition temperature (Tg) of −70° C. to −10° C. and a mass average molecular mass of 100,000 to 1,500,000.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a heat-sensitive adhesive material having a heat-sensitive adhesive layer which is non-adhesive at room temperature, but exhibits adherence by heating and maintains the adherence even after the adherence is exhibited, the heat-sensitive adhesive material having excellent adhesive force particularly to rough-surfaced adherends such as a corrugated board at low temperature environment (0° C.).[0003]2. Description of the Related Art[0004]Recently, label adhesive materials are increasingly used for price labels, product (bar code) labels, quality labels, ingredient labels, and advertisement labels (stickers). As for label recording methods, various methods are developed such as inkjet recording methods, heat-sensitive recording methods, and pressure-sensitive recording methods.[0005]Those label adhesive materials typically have a structure, for example, in which an adhesive layer and release...

AI Technical Summary

Benefits of technology

[0011]An object of the present invention is to provide a heat-sensitive adhesive material excellent in adhesive force to rough-surfaced adherends such as a corrugated board at low temperature environment (0° C.), and having a heat-sensitive adhesive layer which can be thermally activated.

[0012]To solve the above problems, the inventors of the present invention have been intensively studied and found that a heat-sensitive adhesive material containing a support, an adhesive under layer, an intermediate layer and a heat-sensitive adhesive layer formed over a surface of the support in this order, wherein the adhesive under layer containing a thermoplastic resin having a mass average molecular mass of 100,000 to 1,500,000, is formed between the support and the heat-sensitive adhesive layer, thereby allowing the thermoplastic resin in the adhesive under layer to move easily to the heat-sensitive adhesive layer upon thermal activation, and that adhesive force is enhanced. Moreover, the inventors found that the thermoplastic resin does not easily move at low temperature environment, but it easily moves by having a mass average molecular mass of 100,000 to 500,000, thereby exhibiting an effect of enhancing adhesive force.

[0021]The heat-sensitive adhesive material of the present invention contains a support, and an adhesive under layer, an intermediate layer and a heat-sensitive adhesive layer formed over one surface of the support in this order, wherein the intermediate layer contains at least a thermoplastic resin and hollow particles, the heat-sensitive adhesive layer contains at least a thermoplastic resin, an adhesion imparting agent and a thermofusible material, and the adhesive under layer contains at least a thermoplastic resin, the thermoplastic resin has a glass transition temperature (Tg) of −70° C. to −10° C. and a mass average molecular mass of 100,000 to 1,500,000, therefore, the thermoplastic resin in the adhesive under layer easily moves to the heat-sensitive adhesive layer upon thermal activation, thereby enhancing adhesive force, particularly, obtaining excellent adhesive force to rough-surfaced adherends such as a corrugated board at low temperature environment (0° C.).

Problems solved by technology

However, release paper peeled off from an adhesive sheet is hard to be collected and recycled, and in most cases, the peeled release paper discarded subsequently.

However, after the heat-sensitive adhesive exhibits adherence, the adhesive force decreases with a lapse of time.

Moreover, there is a need to apply a high thermal energy when the heat-sensitive adhesive is thermally activated.

These proposals can be relatively effective in reducing thermal energy of the heat-sensitive adhesive, however, the adhesive force to rough-surfaced adherends such as a corrugated board and a polyolefin wrap has not reached the practical level because the water-soluble binder that does not exhibit adherence at room temperature is used therein.

In addition, these proposed heat-sensitive adhesives have not yet resolved a problem that the adhesive force after exhibiting adherence decreases with a lapse of time.

The adhesive under layer mainly contains a thermoplastic resin having a glass transition temperature (Tg) of −70° C. to −10° C. However, the adhesive force of the heat-sensitive adhesive material at low temperature has not yet reached the practical level.

Particularly, adhesive force to rough-surfaced adherends such as a corrugated board at low temperature environment has been a big problem.

However, the adhesive force at low temperature environment (0° C.) has not yet reached the practical level, particularly, a decrease in the adhesive force of the heat-sensitive adhesive material to rough-surfaced adherends such as a corrugated board at low temperature environment has been a significant problem.

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